1. Field of the Invention
The present invention relates to a process and apparatus for developing photopolymer plates. More particular, the present invention relates to a process and apparatus for developing photopolymer plates which are useful for flexographic printing on account of their rubber-like elasticity, capability for development by water washing, and good ink resistance. The process and apparatus of the present invention are so designed as to minimize the aggregation of photopolymer particles suspending in the washout solution and to completely catch scum (polymer dispersion and aggregates thereof) which has separated out from the washout solution in the step of washing out the photopolymer plate.
2. Description of the Prior Art
The photopolymer plates are rapidly coming into general use in various fields of printing because of their better handleability, higher productivity, lower price, and improved printing performance as compared with the conventional printing plates.
There are several types of apparatus in practical use for the development of photopolymer plates. (1) One which forms the relief by blowing off the unexposed part by means of compressed air. (2) One which forms the relief by spraying the washout solution under pressure to the plate. (3) One which forms the relief by rubbing a brush against the plate fixed to a flat surface or cylinder, thereby dissolving the unexposed part in the solution.
The above-mentioned third apparatus suffers from a disadvantage when the washout solution is water (tap water) or surfactant-containing water. The surfactant disperses polymer particles which have been washed out and prevents them from aggregation; however, it does not prevent scum from separating out in the washout solution when the photopolymer is washed out in large quantities and is dispersed in high concentrations in the washout solution. When left unremoved, scum sticks to the developing machine and brush and even to the developed printing plate, causing a serious problem.
As the result of their researches to eliminate the above-mentioned disadvantages, the present inventors developed an improved process and apparatus for the development of photopolymer plates as mentioned in the following.